Differential concrete pump



Aug- 31, 1948 c. l. LoNGENEcKER 2,448,104

DIFFERENTIAL CONCRETE PUMP Filed Dec. 6, 1945 2 Sheets-Sheet l CHARLES l. LONGENECKER IN V EN TOR.

RYA/207g 4,4. m

ATTORNEY E Aug. l31V,v 1948.

c. 1. LoNGENEcKER 2,448,104

DIFFERENTIAL CONCRETE PUMP Filed Dec. 6, 1945 2 Sheets-Shet 2 J7 O a o Figui' 4 0 3s 3 35 o l 7 /2 .ao E, f-

CHARLES l. LONGENECKER INVENTOR.

ATTORNEY Patented Aug. 31,l 1948 l DIFFERENTIAL CONCRETEV PUMP Charles I. Longenecker, Wauwatosa, Wil., al-

lignor to Chain Belt Company, Milwaukee,

Wis., a corporation of Wisconsin Application December 8, 1945, Serial No. 633,091 Claims. (Cl. 1031-108) This invention relates to a pump which may be utilized to force relatively dense, plastic material, such as concrete, through a pipe line to points of use a considerable distance from the source of supply of the material.

It is an object of the present invention to provide a pump for such purposes which is more economical in its construction and more efllcient in operation than pumps heretofore employed.

In one of its essential features, the pump of the present invention utilizes a pair of reciprocating, differential-displacement pistons working in communication with a chamber having inlet and outlet portions and a single valve controlling the passage of material through the chamber in timed relation to the propulsive eifects of the pistons. The use of differential-displacement pistons reciprocating in 180 degree phase relationship, and arranged so that part of the discharge from the large piston is received within the cylinder of the small piston while the balance flows into the line, offers many advantages to a concrete pumping system. One of the most notable advantages is the ability to increase the capacity of the pump without increasing the size of the pipe line required to transmit the concrete.

Experience has demonstrated that there is a maximum velocity for pumping concrete which cannot be exceeded without causing so much friction in the line that pumping becomes impractical. The differential pistons increase the capacity of the pipe without increasing the velocity of flow, because of the increase in frequency of the working strokes of the pistons. Hence, a pipe of small diameter may be employed.

The initial cost of the pipe line is one of the important cost factors ofa concrete pumping system. The present invention enables a reduction in the cost of pipe by approximately one-third for a system of given capacity. By enabling the use of smaller pipe, the individual pipe sections are reduced in weight by over 40 percent, whether weighed full or empty. When I it is realized that a ten foot section of one of the most common sizes of pipe heretofore weighed as much as 230 pounds, when empty, and '780 pounds, when full of concrete,` the tremendous advantage in laying out the pipe line preparatory to pumping, supporting it while concrete is being pumped, and taking it up at the conclusion of the operation, will be apparent.

' The utilization of a single valvein such an arrangement is another important feature of the invention and results in considerable economy because the valve parts used to resist the abrasive action of a gritty material, such as concrete, are necessarily expensive, and where wear does occur requiring frequent replacement of parts, the present invention results in considerable saving. The invention likewise provides means for transmitting concrete through the pipe line in impulses of less duration, thereby making for smoother operation and permits the capacity of the pump to be materially increased with the added advantage that it does not substantially affect the power requirements. Furthermore, the arrangement of the parts is such that a single valve can be employed with two pistons. and the working chamber is kept constantly clean of stagnant bodies of concrete which would otherwise set up, resulting in channeling, and eventually disrupt operations.

Reference may be had to the accompanying drawing illustrating one embodiment of the invention. wherein:

Fig. 1 is a side elevation of the pump; Fig. 2 is a plan view taken in section on the line 2-2 of Fig. 1; Fig. 3 is a side elevation in section taken on the line 3-3 of Fig. 2; and Fig. 4 is a view similar to Fig. 3 showing thevvalve of Fig. 3 in the other position which it occupies. The pump is mounted on any suitable frame or chassis II which may be provided if desired with wheels or other transporting means. A power source (not shown) causes rotation of a gear I2 mounted on a shaft Il journalled on the frame II, and the shaft I3 actuates the pistons and the valve.

Secured to one end of the shaft I3 is a cam Il which actuates rollers I5 and I6 mounted on arms I1 and I8, one on either side of the cam. The arm I1 is pivotally hung from the frame above the cam and the arm I8 is pivotally mounted upon the frame at a point below the cam. The two arms are secured together by a yoke I9 which is slotted to permit the shaft I3 to extend through it and, hence, under the influence of the cam the arm I8 oscillates back and forth and imparts the desired reciprocatory movement to the valve rod 20 which actuates the pump valve 2 I. The surface of the cam provides the required dwell between movements of the valve and causes relatively rapid movementat the end of each stationary period. The amount of throw of the valve may be adjusted by connecting the rod 20 at diierent points on the arm 22, the latter being secured to the end of one of the trunnions extending from the oscillating valve.

The shaft I3 also carries an eccentric 24 on' which is journalled a connecting rod 2l, which is pinned at 2l to a walking beam 21. the ends o! which 'are connected to pistons 28 and 2l working in cylinders l and 3| respectively. Cylinder lll, which is arranged directly above cylinder 3|, has a cross sectional area, as herein shown, oi approximately twice that of cylinder 3| and since the stroke of each piston is the same, it will be clear that the displacement o! the large piston is twice that oi the smaller.

The valve housing, or working chamber 32, is arranged to be readily assembled or disassembled in communication with the ends of the cylinders 30 and 3|. and for this purpose openings arel provided in the valve housing which will register with the ends of the cylinders, and gaskets 33 may be employed to seal the connection. A pair of chains 34 are secured to the frame below the valve housing and may be drawn over suitable tracks on the exterior of the housing and coupled by quick acting levers 35 secured to chains 3B extending over the top of the housing to points oi securement on the frame.

Adjustment of the length of each chain strand may be made by taking up a nut I1, which bears against a suitable bracket 38 mounted on the frame and is threaded on a rod 39 secured to one end of the chain and extending through an aperture in the bracket. Ready disassembly o i the valve housing froml the cylinder is highly desirable in order to permit replacement of the entire valve chamber and valve with a new assembly where job conditions require continuous, uninterrupted operation. The present invention permits replacement to be made in as short a time as ilfteen minutes, which ordinarily permits resumption of pumping without requiring a clean-out of the entire pipe line.

The top of the valve housing 32 is provided with an inlet opening 40, which is of the same order of size as the cross section of the large cylinder 30. This opening leads downward and communicates with the inlet portion of the working chamber, the latter including a portion which is cylindrical in shape about a horizontal axis extendi g at right angles to the direction oi movement f the pistons 28 and 29. The axis of the cylindrical portion is in nearly the same horizontal plane as the axis of the cylinder 30. Mounted tightly in the cylindrical portion of the valve housing is a cylindrical liner 4| of hard, abrasion-resisting material having three ports which communicate with: ilrst, the inlet to the pump; second, the passage leading to the large cylinder 30; and third, the outlet which communicates with the smaller cylinder 3| and the discharge outlet from the pump. The last mentioned port is disposed in the lower left hand quadrant of the liner 4|, as shown in Fig. 3, and the upper end of it is substantially above the bottom of the cylinder 30.

Mounted for oscillating movement within the valve housing is a plug valve 2| having suitable i clearance with the liner 4| referred to above. The end portions 42 of the valveplug are provided with trunnions 43 journalled in bearings mounted by spiders 44 secured by bolts 45 to the housing. Attached to the outer end oi one of the trunnions is the aforementioned arm 22 which oscillates the valve. r

The end portions of the valve 2| arefull cylinders and the intermediate portion is channeled out at 46 to provide passages for ilow 'oi material through the valve. The ends of the liner 4| are retained by rings 46' to which the spiders 44 are secured and extending through these rings are the bolts 4l which support the valve in the housing 32. It desired, packing may be inserted between the ends of the valve plug and the housing.

In Fig. 3 the valve is shown in the position it occupies while concrete is lbeing drawn into the large cylinder 30. It will be seen that in this position the valve does not entirely close the outlet port in the liner 4|, but it blocks it suillciently so that when pumping material, such as concrete, there is no back-iiow from the line because oi' the stowing characteristic of concrete. When in this position, the piston 28 is drawing concrete through the inlet opening 40 and into the piston working cylinder I0.

As previously stated the amount of movement of the valve may be adjusted so that the degree of closure may vary to meet the requirements of diiierent concretemixtures. In some cases it may be desirable to close the openings entirely and the invention is therefore not to be limited in this respect.

The lower part of the working chamber is provided with an outlet 41, the top oi which is only slightly below the top oi the outlet port in the valve liner plate 4|, and the bottom of which siopesI downward to the bottcm of the small cylinder ranged closely adjacent the bottom oi the valve plug, but is onset as shown in Fig. 3 from the end of the cylinder 30 so that the entrance to the cylinder 3| is substantially in vertical alignment with the lower edge of the outlet opening of the liner sleeve 4|. With the valve as shown in Fig. 3, the smaller piston 29 is expelling concrete through the outlet 41 through a channel, which is not materially larger in cross section than the cross section of the piston 2Q, and back-flow into the larger cylinder is eil'ectively prevented by the aforesaid valve.

As the pistons are completing their respective strokes, i.e., the large piston drawing in concrete while the small piston is expelling it, the valve is oscillated to the position shown in Fig. 4, in which position theinlet 40 to the pump, while not entirely closed tor pumping concrete, is sufficiently closed so that the full propulsiva eect of the large piston 28 causes movement of the concrete from the cylinder 30 through the valve and the outlet passage in the liner 4|.

Not all the concrete expelled by the large cylinder goes into the pipe line 48 which communicates with the outlet opening 41, but instead approximately half of this expelled concrete is forced into the smaller cylinder 3| during the return stroke of the latter. Since the two pistons are each connected to the walking beam 21, the pressure which the concrete exerts on the face of the piston 29 reduces by substantially one-half the load which the engine would otherwise have to exert on concrete in the large cylinder.

The remainder of the concrete expelled by the large cylinder i.e., the excess which does not go into the cylinder 3|, passes through the outlet 41 into the pipe line, and as previously stated, the amount of concrete so discharged is quantitatively equal to the amount expelled by the small piston during its propulsion stroke. The pipe line need only be large enough in cross section to accommodate the displacement of the small piston, and in practice it should be of the same order as the cross sectional area of the cylinder in which the small piston operates.

By providing a continuously open and substantially unobstructed passage in the lower or outlet The top of the small cylinder 3| is arportion oitheworking chamber connecting the outlet sec'tion and the pipe line with the smaller cylinder, concrete may ilow in a direct path to the outlet when the small piston is exerting pressure.` When the valve is shifted to its other position, thereby providing a lateral opening in this passageway, concrete under pressure from,the large piston may now through the valve in a substantially straight path to the outlet section. This results from the disposition of the outlet section on the opposite side of the working chamber from the pressure members and in substantially parallel but overlapping relation with respect to each. The arrangement of these passages is an important feature of the invention as it is applied to the art or pumpingmaterial such as concrete. for unless properly arranged, the pump may clog and cause an interruption o! operations.

The invention lhaving been described, what is claimed is:

l. A pump for concrete and the like comprising a working chamber having an inlet portion and an outlet portion. a pair of cylinders communieating with said respective portions, reciprocating pistonsoperating in timed relation in said cylinders to create pressure alternately in said chamber portions, the piston creating pressure vin the 'inlet portion having greater displacement than the piston creating pressure in the outlet portion, and a single valve disposed within the inlet portion movable to check alternately backilow during the pressure strokes of the respective pistons, said valve during the suction stroke of the larger piston providing communication between the inlet of the pump and the cylinder containing the larger piston and during the suction stroke of the smaller piston providing com munication between the two cylinders.

2. A pump for concrete and the like comprising a working chamber having an inlet portion and an outlet portion, a pair of cylinders communicating with said respective portions, reciprocating pistons operating in timed relation in said cylinders to create pressure alternately in said chamber portions, the piston creating pressure in the inlet portion having greater displacement than the piston creating pressure in the outlet portion, means interconnecting the pistons so that pressure exerted on the piston having lesser displacement reduces the load on the other piston, and a single valve disposed within the inlet portion movable to check alternately back-flow during the pressure strokes of the respective pistons, said valve during the suction stroke of the larger piston providing communication between the inlet of the pump and the cylinder containing the larger piston and during the suction stroke of the smaller piston providing communication between the two cylinders.

3. A pump for plastic concrete mixtures, comprising adjacent open-ended primary and secondary working cylinders; a chamber adjoining and communicating with the open ends of the respective cylinders, said chamber also having an inlet and an outlet, the latter beingin constant open communication with said secondary cylinder and disposed to receive substantially unobstructed discharge from each cylinderi means for alternately expelling the plastic mixture from the respective cylinders in diierential quantities, those discharged from the primary cylinder being greater than those discharged from the secondary cylinder: a single valve in said chamber for placing the primary cylinder in communication with the chamber inlet during the discharge period of inlet, and establishing communication between y said cylinder and the chamber, whereby a portion oi' the mixture discharged from the primary cylinder may pass through the chamber to the secondary cylinder while the remaining portion will Atraverse the chamber to the outlet; and means for actuating said valve.

4. A pump for forcing plastic concrete material and the like through a pipe line, comprising a ,cylinder having an open end; a piston reciprocatable in said cylinder; means connectedvto the cylinder providing a continuously open substantially unobstructed passageway leading from said open cylinder end to the pipe line, said passageway having a lateral port through which the material may be supplied thereto; a valve controlling said port; means for actuating said valve in timed relation to the movements of said piston, whereby to substantially close the port during the pressure stroke of the piston to prevent back-ilow of the material through the port, and to open the port during the return stroke` of the piston; andl mechanism operable while the valve is open to force through said port and passageway a quantity of material in excess of the displacement of the piston, whereby to supply a charge of material to said cylinder and simultaneously discharge a portion of the material to the pipeline.

5. A pump for concrete and the like comprising a working chamber having an upper portion communicating with an inlet and a lower portion in constantly open communication with an outlet to which a pipe line may be attached,a pair of open-ended cylinders communicating with said portions, pistons exerting pressure alternately in said cylinders, the piston exerting pressure in the cylinder connected to the lower portion of said chamber having less displacement than the other piston, and a single valve disposed within the upper portion of the chamber arranged to check backilow from the lower to the upper portion of the chamber duringlthe pressure stroke of the piston having less displacement while providing communication between the inlet and the cylinder containing the other piston, said valve being movable to another position for checking back-flow through the inlet while directing flow from the upper portion into the lower portion during the pressure stroke of the piston having greater displacement.

6. A pump for pumping concrete and the like through a pipe line comprising a working chamber having an inlet portion and an outlet portion, said outlet portion having an open ,passageway leading into the pipe line and a lateral port communicating with the inlet portion of the chamber, a cylinder communicating with the endI of the passageway and forming an extension thereof, a second cylinder of larger cross sectional area communicating with the inlet portion oi the chamber, pistons operating in said cylinders in degree phase relation, and a single valve disposed within the inlet portion arranged to alternately check back-flow from the pistons during their pressure strokes.

7. A pump for pumping plastic material such as concrete comprising a working chamber having an inlet and an outlet portion, substantially tion oi' the chamber arranged to check back-flow from the pistons during their respective pressure strokes, said valve when checking back-dow from the larger piston providing a substantially straight path from the larger cylinder to the outlet section.

8. In a pump for plastic concrete mixtures and the like. a working chamber having an upper inlet portion and a lower outlet portion, an outlet section in the outlet portion extending from one side olf the chamber, substantially parallel cylinders communicating with said portions respectively and extending from the opposite side oi' the chamber, the cylinder communicating with the inlet portion of the chamber having greater crosssectional area than the other cylinder, pistons operating alternately in said cylinders. and an oscillating plug valve disposed within the inlet portion of the chamber arranged to check alternately back-flow from the pistons, said valve when checking back-ilow from the larger piston 'providing a substantially straight path from the larger cylinder to the outlet section.

, 9. In a differential piston concrete pump having an inlet and an outlet and a working chamber including a pair of cylinders with alternately operating pistons disposed therein whose face areas are in the ratio oi.' substantially two to one, a single mechanically operated valve disposed within the chamber arranged to alternately check back-flow `irom the pistons during their respective pressure strokes. said valve while checking back-flow from the smaller piston admitting concrete through the inlet of the pump. and while checking back-now l0 from the larger piston, providing communication between said cylinders.

10. In a differential piston concrete pump having an inlet and an outlet and a working chamber including a pair of cylinders with alternately 15 operating pistons disposed therein whose tace areas are in the ratio oi'substantiallytwo to one, a single oscillating plug valve disposed within the chamber arranged to alternately check backnow from the pistons during their respective presn sure strokes. said valve while checking backflow from the smaller piston admitting concrete through the inlet oi' the pump, and while checking back-flow from the larger piston. providing communication between said cylinders.

CHARLES I. IDNGENECKER.

REFERENCES crrnn The following references are of record in the ille oi this patent:`

UNITED s'rA'rEsPATENTs Brown June 25, 1940 

